1. Department of Civil Engineering National Taiwan University No. 1, Sec. 4, Roosevelt Rd. Taipei 10617 Taiwan
2. Laboratory for Atomistic and Molecular Mechanics (LAMM) Massachusetts Institute of Technology 77 Massachusetts Ave. Cambridge MA 02139 USA
3. Department of Engineering Science National Cheng Kung University No. 1, University Road Tainan City 701 Taiwan
4. Center for Computational Science and Engineering Schwarzman College of Computing Massachusetts Institute of Technology 77 Massachusetts Ave. Cambridge MA 02139 USA
5. Center for Materials Science and Engineering 77 Massachusetts Ave. Cambridge MA 02139 USA